My 15yr old son woke up with a swollen normal skin colored bump just under his middle knuckle of his middle finger. It is squishy and doesn't hurt him at all.He plays the tbone this is where the tbone rests when he holds it to play. He had an MRI done

MRI showed some kind "mass that doesn't invade bone, maybe a vascular structure, most likely a hemangioma" recommend a doppler ultrasound.
Ultrasound shows a "vague, subcutaneous fusiform and expansile lesion that might resemble a vascular lesion. However, THERE IS NO INTERNAL FLOW so I am uncertain about this finding but suspect that this represents a thrombosed AVM malformation"

The hand surgeon said she wants to surgically remove it and then they will know what type of malformation it is.
This doesn't seem right to me. I don't want to put him under general anesthesia unless I know exactly what is wrong. Everybody in these forums seems to know what is wrong with them whether it is a hemangioma, a lymphatic mf, a venous mf or an AVM. Am I crazy to want to know exactly what is wrong before operating and does he even have to have surgery can't we just wait and see if it will go away? (The dr is from Childrens Hospital in Philadelphia.) Can anybody help me or direct me and can I get a second opinion?
I would appreciate anyones thoughts on this...

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